As Moore's Law drives the bandwidth of data buses increasingly higher, fundamental roadblocks associated with traditional microstrip and stripline transmission line structures limit channel speeds to frequencies lower than 15-20 gigabits per second. The signaling limits are fundamentally associated with transmission line losses caused by both the dielectric and the copper as well as the propagation modes supported by the microstrip and stripline structures. Further, the implementation of high performance dielectrics with standard transmission line structures might provide a minimal increase in bandwidth but at a significant increase in cost.
As signaling frequencies and carrier frequencies for modulated signals rise beyond 15-20 gigabits per second and increase toward 20-50 GHz and beyond, the standard microstrip and stripline structures become less effective as transmission structures. An alternative method of signal propagation is therefore required. In order to ensure a minimal loss and to guide the energy of such high frequencies, one solution might be to use waveguide structures. Waveguides are typically devices that control the propagation of an electromagnetic wave so that the wave is forced to follow a path defined by the physical structure of the guide. Standard waveguides cannot easily be integrated within a digital system based on current printed circuit board (PCB) process technology. Therefore, a need has arisen for an improved PCB waveguide.